Dissecting the genetics of athletic performance and conformation traits in horses

Abstract: The overall aims of this thesis were to investigate the genetics of athletic performance and the level of inbreeding in Coldblooded trotters, as well as the genetics of conformation traits in Icelandic horses. In paper I, genomic-based inbreeding coefficients in Coldblooded trotters were estimated and compared with pedigree-based coefficients. The results showed that the inbreeding level has gradually increased during the investigated years 2000-2009 and that genomic measures of inbreeding could be used to minimize further increased inbreeding. In papers II-IV, different genetic mapping methods were used to dissect the genetics of athletic performance in Coldblooded trotters. The results from papers II and III indicated that athletic performance requires not only physical characteristics but also mental qualities such as memory and learning. In paper IV, we investigated the genetics of athletic performance and exercise related blood pressure. An associated haplotype to these traits was identified. The relative quantitative proteomics analysis showed that proteins linked to inflammatory and coagulation processes were differentially expressed between the elite and sub-elite performing haplotype groups at rest and during exercise. In paper V, we performed a genome-wide association study in Icelandic horses assessed at breeding field tests to dissect the genetics of conformation of back and croup. A quantitative trait locus for conformation of back and croup and quality of lateral gaits was identified. The genomic region harbored genes linked to anthropometric traits, scoliosis, and motor laterality in humans. In conclusion, this thesis contributes to increased knowledge about the genetics of complex traits such as athletic performance, blood pressure regulation, inflammation, and anthropometric traits in horses. This information may also be of value for humans and other mammalian species.

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